Btrfs: While doing checksums on bios, cache the extent_buffer mapping
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 3f0e71b..ee25e50 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -156,6 +156,11 @@
int bio_index = 0;
struct bio_vec *bvec = bio->bi_io_vec;
char *data;
+ char *eb_map;
+ char *eb_token;
+ unsigned long map_len;
+ unsigned long map_start;
+
path = btrfs_alloc_path();
BUG_ON(!path);
@@ -272,6 +277,7 @@
item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
btrfs_item_size_nr(leaf, path->slots[0]));
+ eb_token = NULL;
next_bvec:
data = kmap_atomic(bvec->bv_page, KM_IRQ0);
csum_result = ~(u32)0;
@@ -283,15 +289,39 @@
printk("csum result is 0 for inode %lu offset %Lu\n", inode->i_ino, offset);
}
- write_extent_buffer(leaf, &csum_result, (unsigned long)item,
- BTRFS_CRC32_SIZE);
+ if (!eb_token ||
+ (unsigned long)item + BTRFS_CRC32_SIZE >= map_start + map_len) {
+ int err;
+
+ if (eb_token)
+ unmap_extent_buffer(leaf, eb_token, KM_IRQ1);
+ eb_token = NULL;
+ err = map_private_extent_buffer(leaf, (unsigned long)item,
+ BTRFS_CRC32_SIZE,
+ &eb_token, &eb_map,
+ &map_start, &map_len, KM_IRQ1);
+ if (err)
+ eb_token = NULL;
+ }
+ if (eb_token) {
+ memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
+ &csum_result, BTRFS_CRC32_SIZE);
+ } else {
+ write_extent_buffer(leaf, &csum_result, (unsigned long)item,
+ BTRFS_CRC32_SIZE);
+ }
bio_index++;
bvec++;
if (bio_index < bio->bi_vcnt) {
- item = (struct btrfs_csum_item *)((char *)item + BTRFS_CRC32_SIZE);
+ item = (struct btrfs_csum_item *)((char *)item +
+ BTRFS_CRC32_SIZE);
if (item < item_end)
goto next_bvec;
}
+ if (eb_token) {
+ unmap_extent_buffer(leaf, eb_token, KM_IRQ1);
+ eb_token = NULL;
+ }
btrfs_mark_buffer_dirty(path->nodes[0]);
if (bio_index < bio->bi_vcnt) {
btrfs_release_path(root, path);